Levodopa Dose Equivalency in Parkinson's Disease: Updated Systematic Review and Proposals

BACKGROUND

To compare drug regimens across clinical trials in Parkinson's disease (PD) conversion formulae between antiparkinsonian drugs have been developed. These are reported in relation to levodopa as the benchmark drug in PD pharmacotherapy as 'levodopa equivalent dose' (LED). Currently, the LED conversion formulae proposed in 2010 by Tomlinson et al. based on a systematic review are predominantly used. However, new drugs with established and novel mechanisms of action and novel formulations of longstanding drugs have been developed since 2010. Therefore, consensus proposals for updated LED conversion formulae are needed.

OBJECTIVES

To update LED conversion formulae based on a systematic review.

METHODS

The MEDLINE, CENTRAL, and Embase databases were searched from January 2010 to July 2021. Additionally, in a standardized process according to the GRADE grid method, consensus proposals were issued for drugs with scarce data on levodopa dose equivalency.

RESULTS

The systematic database search yielded 3076 articles of which 682 were eligible for inclusion in the systematic review. Based on these data and the standardized consensus process, we present proposals for LED conversion formulae for a wide range of drugs that are currently available for the pharmacotherapy of PD or are expected to be introduced soon.

CONCLUSIONS

The LED conversion formulae issued in this Position Paper will serve as a research tool to compare the equivalence of antiparkinsonian medication across PD study cohorts and facilitate research on the clinical efficacy of pharmacological and surgical treatments as well as other non-pharmacological interventions in PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Benefits and Risks of a Staged‐Bilateral VIM versus Unilateral VIM DBS for Essential Tremor

Background

Despite over 30 years of clinical experience, high‐quality studies on the efficacy of bilateral versus unilateral deep brain stimulation (DBS) of the ventral intermediate (VIM) nucleus of the thalamus for medically refractory essential tremor (ET) remain limited.

Objectives

To compare benefits and risks of bilateral versus unilateral VIM DBS using the largest ET DBS clinical trial dataset available to date.

Methods

Participants from the US St. Jude/Abbott pivotal ET DBS trial who underwent staged‐bilateral VIM implantation constituted the primary cohort in this sub‐analysis. Their assessments “on” DBS at six months after second‐side VIM DBS implantation were compared to the assessments six months after unilateral implantation. Two control cohorts of participants with unilateral implantation only were also used for between‐group comparisons.

Results

The primary cohort consisted of n = 38 ET patients (22M/16F; age of 65.3 ± 9.5 years). The second side VIM‐DBS resulted in a 29.6% additional improvement in the total motor CRST score (P < 0.001), with a 64.1% CRST improvement in the contralateral side (P < 0.001). An added improvement was observed in the axial tremor score (21.4%, P = 0.005), and CRST part B (24.8%, P < 0.001) score. Rate of adverse events was slightly higher after bilateral stimulation.

Conclusions

In the largest ET DBS study to date, staged‐bilateral VIM DBS was a highly effective treatment for ET with bilateral implantation resulting in greater reduction in total motor tremor scores when compared to unilateral stimulation alone.

European Academy of Neurology guidance for developing and reporting clinical practice guidelines on rare neurological diseases

BACKGROUND AND PURPOSE

Rare diseases affect up to 29 million people in the European Union, and almost 50% of them affect the nervous system or muscles. Delays in diagnosis and treatment onset and insufficient treatment choices are common. Clinical practice guidelines (CPGs) may improve the diagnosis and treatment of patients and optimize care pathways, delivering the best scientific evidence to all clinicians treating these patients. Recommendations are set for developing and reporting high-quality CPGs on rare neurological diseases (RNDs) within the European Academy of Neurology (EAN), through a consensus procedure.

METHODS

A group of 27 experts generated an initial list of items that were evaluated through a two-step Delphi consensus procedure and a face-to-face meeting. The final list of items was reviewed by an external review group of 58 members.

RESULTS

The consensus procedure yielded 63 final items. Items are listed according to the domains of the AGREE instruments and concern scope and purpose, stakeholder involvement, rigour of development, and applicability. Additional items consider reporting and ethical issues. Recommendations are supported by practical examples derived from published guidelines and are presented in two tables: (1) items specific to RND CPGs, and general guideline items of special importance for RNDs, or often neglected; (2) items for guideline development within the EAN.

CONCLUSIONS

This guidance aims to provide solutions to the issues specific to RNDs. This consensus document, produced by many experts in various fields, is considered to serve as a starting point for further harmonization and for increasing the quality of CPGs in the field of RNDs.

Subthalamic and pallidal deep brain stimulation for Parkinson's disease-meta-analysis of outcomes

Although deep brain stimulation (DBS) of the globus pallidus internus (GPi) and the subthalamic nucleus (STN) has become an established treatment for Parkinson’s disease (PD), a recent meta-analysis of outcomes is lacking. To address this gap, we performed a meta-analysis of bilateral STN- and GPi-DBS studies published from 1990-08/2019. Studies with ≥10 subjects reporting Unified Parkinson’s Disease Rating Scale (UPDRS) III motor scores at baseline and 6–12 months follow-up were included. Several outcome variables were analyzed and adverse events (AE) were summarized. 39 STN studies (2035 subjects) and 5 GPi studies (292 subjects) were eligible. UPDRS-II score after surgery in the stimulation-ON/medication-OFF state compared to preoperative medication-OFF state improved by 47% with STN-DBS and 18.5% with GPi-DBS. UPDRS-III score improved by 50.5% with STN-DBS and 29.8% with GPi-DBS. STN-DBS improved dyskinesia by 64%, daily OFF time by 69.1%, and quality of life measured by PDQ-39 by 22.2%, while Levodopa Equivalent Daily Dose (LEDD) was reduced by 50.0%. For GPi-DBS information regarding dyskinesia, OFF time, PDQ-39 and LEDD was insufficient for further analysis. Correlation analysis showed that preoperative L-dopa responsiveness was highly predictive of the STN-DBS motor outcome across all studies. Most common surgery-related AE were infection (5.1%) and intracranial hemorrhage (3.1%). Despite a series of technological advances, outcomes of modern surgery are still comparable with those of the early days of DBS. Recent changes in target selection with a preference of GPi in elderly patients with cognitive deficits and more psychiatric comorbidities require more published data for validation.

The economic benefit of timely, adequate, and adherence to Parkinson's disease treatment: the Value of Treatment Project 2

BACKGROUND

Parkinson's disease (PD) is a chronic progressive neurological disorder with a high psychosocial and economic burden. As part of the European Brain Council (EBC)-led Value of Treatment project, this study aimed to capture the economic benefit of timely, adequate, and adherence to PD treatment.

METHODS

The EBC Value of Treatment Initiative combined different stakeholders to identify unmet needs in the patients' journey according to Rotterdam methodology. The economic evaluation focused on three major topics identified as major gaps: start of treatment; best treatment for advanced disease; and adherence to treatment. Two separate healthcare systems (Germany and the UK) were chosen. Cost-effectiveness was determined by using decision-analytical modelling approaches. Effectiveness was expressed as quality-adjusted life-years (QALYs) gained and incremental cost-effectiveness ratio (ICER).

RESULTS

Treatment intervention in PD was found to be cost-effective regardless of the initial health state of the patient receiving the treatment. Cost savings were between -€1000 and -€5400 with 0.10 QALY gain and -€1800 and -€7600 with 0.10 QALY gain for Germany and the UK, respectively. Treatment remains cost-effective within the National Institute for Health and Care Excellence thresholds. Availability of adequate treatment to more patients was also found to be cost-effective, with an ICER of €15,000-€32,600 across country settings. Achieving the target adherence to treatment would generate cost-savings of €239,000-€576,000 (Germany) and €917,000-€2,980.000 (UK) for every 1,000 patients treated adequately.

CONCLUSIONS

The analyses confirmed that timely, adequate, and adherence to PD treatment will not only improve care of the patients but is also cost-effective across healthcare systems. Further studies with a distinct identification of gaps in care are necessary to develop better and affordable care.

Discrimination of physiological tremor from pathological tremor using accelerometer and surface EMG signals

BACKGROUND AND OBJECTIVE: Although careful clinical examination and medical history are the most important steps towards a diagnostic separation between different tremors, the electro-physiological analysis of the tremor using accelerometry and electromyography (EMG) of the affected limbs are promising tools. METHODS: A soft-decision wavelet-based decomposition technique is applied with 8 decomposition stages to estimate the power spectral density of accelerometer and surface EMG signals (sEMG) sampled at 800 Hz. A discrimination factor between physiological tremor (PH) and pathological tremor, namely, essential tremor (ET) and the tremor caused by Parkinson’s disease (PD), is obtained by summing the power entropy in band 6 (B6: 7.8125–9.375 Hz) and band 11 (B11: 15.625–17.1875 Hz). RESULTS: A discrimination accuracy of 93.87% is obtained between the PH group and the ET & PD group using a voting between three results obtained from the accelerometer signal and two sEMG signals. CONCLUSION: Biomedical signal processing techniques based on high resolution wavelet spectral analysis of accelerometer and sEMG signals are implemented to efficiently perform classification between physiological tremor and pathological tremor.

Insufficiency of trunk extension and impaired control of muscle force in Parkinson's disease with camptocormia

OBJECTIVE

To examine the aetiology of parkinsonian camptocormia, a non-fixed pathological forward bending of the trunk, by measuring trunk muscle activation and force regulation in Parkinson patients with (PD + CC) and without (PD) camptocormia matched for disease severity, and in age- and sex-matched healthy controls (HC).

METHODS

The isometric forces of trunk extension and flexion were measured in PD + CC, PD and HC. Neuromuscular efficiency (increase of extension force per increase of paravertebral muscle surface electromyography signal) and the ability to maintain a constant submaximal trunk extension force were examined.

RESULTS

Peak trunk extension force was significantly lower in PD + CC and PD than in HC, with PD + CC non-significantly weaker than PD. Compared with HC and with PD, the neuromuscular efficiency of trunk extension was significantly reduced in PD + CC. The variability of the force output (coefficient of variation) was significantly larger for PD + CC than for HC or PD.

CONCLUSION

The reduced neuromuscular efficiency of trunk extension separates PD + CC from PD. Moreover, control of the trunk extensor force is impaired in PD + CC.

SIGNIFICANCE

There is weakness and a force control deficit in parkinsonian camptocormia suggesting a disturbed sensory-motor integration, which may contribute to myopathic changes in the trunk extensor muscles.

Serum neuronal exosomes predict and differentiate Parkinson's disease from atypical parkinsonism

OBJECTIVE

Parkinson's disease is characterised neuropathologically by α-synuclein aggregation. Currently, there is no blood test to predict the underlying pathology or distinguish Parkinson's from atypical parkinsonian syndromes. We assessed the clinical utility of serum neuronal exosomes as biomarkers across the spectrum of Parkinson's disease, multiple system atrophy and other proteinopathies.

METHODS

We performed a cross-sectional study of 664 serum samples from the Oxford, Kiel and Brescia cohorts consisting of individuals with rapid eye movement sleep behavioural disorder, Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, frontotemporal dementia, progressive supranuclear palsy, corticobasal syndrome and controls. Longitudinal samples were analysed from Parkinson's and control individuals. We developed poly(carboxybetaine-methacrylate) coated beads to isolate L1 cell adhesion molecule (L1CAM)-positive extracellular vesicles with characteristics of exosomes and used mass spectrometry or multiplexed electrochemiluminescence to measure exosomal proteins.

RESULTS

Mean neuron-derived exosomal α-synuclein was increased by twofold in prodromal and clinical Parkinson's disease when compared with multiple system atrophy, controls or other neurodegenerative diseases. With 314 subjects in the training group and 105 in the validation group, exosomal α-synuclein exhibited a consistent performance (AUC=0.86) in separating clinical Parkinson's disease from controls across populations. Exosomal clusterin was elevated in subjects with non-α-synuclein proteinopathies. Combined neuron-derived exosomal α-synuclein and clusterin measurement predicted Parkinson's disease from other proteinopathies with AUC=0.98 and from multiple system atrophy with AUC=0.94. Longitudinal sample analysis showed that exosomal α-synuclein remains stably elevated with Parkinson's disease progression.

CONCLUSIONS

Increased α-synuclein egress in serum neuronal exosomes precedes the diagnosis of Parkinson's disease, persists with disease progression and in combination with clusterin predicts and differentiates Parkinson's disease from atypical parkinsonism.

Neurogeriatrics-a vision for improved care and research for geriatric patients with predominating neurological disabilities

Geriatric medicine is a rapidly evolving field that addresses diagnostic, therapeutic and care aspects of older adults. Some disabilities and disorders affecting cognition (e.g. dementia), motor function (e.g. stroke, Parkinson’s disease, neuropathies), mood (e.g. depression), behavior (e.g. delirium) and chronic pain disorders are particularly frequent in old subjects. As knowledge about these age-associated conditions and disabilities is steadily increasing, the integral implementation of neurogeriatric knowledge in geriatric medicine and specific neurogeriatric research is essential to develop the field. This article discusses how neurological know-how could be integrated in academic geriatric medicine to improve care of neurogeriatric patients, to foster neurogeriatric research and training concepts and to provide innovative care concepts for geriatric patients with predominant neurological conditions and disabilities.

Differences in neurology residency training programmes across Europe - a survey among the Residents and Research Fellow Section of the European Academy of Neurology national representatives

BACKGROUND AND PURPOSE

Neurology is rapidly evolving as a result of continuous diagnostic and therapeutic progress, which influences the daily work of neurologists. Therefore, updating residency training programmes is crucial for the future of neurology. Several countries are currently discussing and/or modifying the structure of their neurology residency training programme. A detailed and up-to-date overview of the available European residency training programmes will aid this process.

METHODS

A questionnaire addressing numerous aspects of residency training programmes in neurology was distributed among 38 national representatives of the Resident and Research Fellow Section of the European Academy of Neurology.

RESULTS

We obtained data from 32 European countries (response rate 84%). The median (range) duration of the residency training programmes was 60 (12-72) months. In the majority of countries, rotations to other medical disciplines were mandatory, mostly psychiatry (69%), internal medicine (66%) and neurosurgery (59%). However, the choice of medical fields and the duration of rotations varied substantially between countries. In 50% of countries, there were formal regulations regarding training in evidence-based medicine, teaching skills and/or leadership qualities. In many countries (75%), residents had to take an examination.

CONCLUSIONS

We found substantial variation among European countries in the duration of residency training programmes, and especially in the choice of obligatory rotations to external medical disciplines. Despite a presumably similar spectrum of patients, neurology residency training programmes across Europe are not harmonized. The structure of the programme should be determined by its relevance for neurologists today and in the future.

[The new tremor classification of the International Parkinson and Movement Disorder Society : Update on frequent tremors]

Tremor is one of the most frequent movement disorders. The recently published new classification of the Movement Disorder Society separates the clinical description of tremor syndromes as so-called axis 1 symptom constellations from the etiologies of tremor (axis 2). The same tremor syndromes can therefore be combined with different causes and vice versa. The terminology used in this classification is precisely defined and thereby also the necessary language for medical communication. Frequent tremor syndromes, such as enhanced physiologic tremor, dystonic and parkinsonian tremor as well as focal tremors and task and position-specific tremors are discussed with respect to the phenomenology, and current therapy.

The spectrum of progressive multifocal leukoencephalopathy: a practical approach

John Cunningham virus (JCV) infection of the central nervous system causes progressive multifocal leukoencephalopathy (PML) in patients with systemic immunosuppression. With the increased application of modern immunotherapy and biologics in various immune-mediated disorders, the PML risk spectrum has changed. Thus, new tools and strategies for risk assessment and stratification in drug-associated PML such as the JCV antibody indices have been introduced. Imaging studies have highlighted atypical presentations of cerebral JCV disease such as granule cell neuronopathy. Imaging markers have been developed to differentiate PML from new multiple sclerosis lesions and to facilitate the early identification of pre-clinical manifestations of PML and its immune reconstitution inflammatory syndrome. PML can be diagnosed either by brain biopsy or by clinical, radiographic and virological criteria. Experimental treatment options including immunization and modulation of interleukin-mediated immune response are emerging. PML should be considered in any patient with compromised systemic or central nervous system immune surveillance presenting with progressive neurological symptoms.

Randomized Delayed-Start Trial of Levodopa in Parkinson's Disease

BACKGROUND

Levodopa is the main treatment for symptoms of Parkinson's disease. Determining whether levodopa also has a disease-modifying effect could provide guidance as to when in the course of the disease the treatment with this drug should be initiated.

METHODS

In a multicenter, double-blind, placebo-controlled, delayed-start trial, we randomly assigned patients with early Parkinson's disease to receive levodopa (100 mg three times per day) in combination with carbidopa (25 mg three times per day) for 80 weeks (early-start group) or placebo for 40 weeks followed by levodopa in combination with carbidopa for 40 weeks (delayed-start group). The primary outcome was the between-group difference in the mean change from baseline to week 80 in the total score on the Unified Parkinson's Disease Rating Scale (UPDRS; scores range from 0 to 176, with higher scores signifying more severe disease). Secondary analyses included the progression of symptoms, as measured by the UPDRS score, between weeks 4 and 40 and the noninferiority of early initiation of treatment to delayed initiation between weeks 44 and 80, with a noninferiority margin of 0.055 points per week.

RESULTS

A total of 445 patients were randomly assigned: 222 to the early-start group and 223 to the delayed-start group. The mean (±SD) UPDRS score at baseline was 28.1±11.4 points in the early-start group and 29.3±12.1 points in the delayed-start group. The change in UPDRS score from baseline to week 80 was -1.0±13.1 points and -2.0±13.0 points, respectively (difference, 1.0 point; 95% confidence interval [CI], -1.5 to 3.5; P=0.44); this finding of no significant between-group difference at week 80 implies that levodopa had no disease-modifying effect. Between weeks 4 and 40, the rate of progression of symptoms, as measured in UPDRS points per week, was 0.04±0.23 in the early-start group and 0.06±0.34 in the delayed-start group (difference, -0.02; 95% CI, -0.07 to 0.03). The corresponding rates between weeks 44 and 80 were 0.10±0.25 and 0.03±0.28 (difference, 0.07; two-sided 90% CI, 0.03 to 0.10); the difference in the rate of progression between weeks 44 and 80 did not meet the criterion for noninferiority of early receipt of levodopa to delayed receipt. The rates of dyskinesia and levodopa-related fluctuations in motor response did not differ significantly between the two groups.

CONCLUSIONS

Among patients with early Parkinson's disease who were evaluated over the course of 80 weeks, treatment with levodopa in combination with carbidopa had no disease-modifying effect. (Funded by the Netherlands Organization for Health Research and Development and others; LEAP Current Controlled Trials number, ISRCTN30518857 .).

Life-threatening DBS withdrawal syndrome in Parkinson's disease can be treated with early reimplantation

INTRODUCTION

The deep brain stimulation (DBS) withdrawal syndrome (DBS-WDS) is a rare, life-threatening complication in Parkinson's disease (PD) patients with long disease duration and stimulation when stimulation is terminated for extended periods mostly due to infection of the DBS-hardware.

METHODS, RESULTS

In five patients explantation became necessary because of infection after a mean of 11.4 years (range 4-15 years) of DBS and a mean disease duration of 24.6 years (range 3-22 years). Mean UPDRS motor-score pre-explantation was 38 points (range 24-55 points) which increased to a mean of 78.4 points (range 58-90 points) after explantation, despite optimal Levodopa dosing. Reimplantation of the hardware after 23 days (range 3-45 days) under antibiotic treatment led to an improvement to a mean of 40 points (range 25-73 points) and a complication free survival.

CONCLUSION

Early reimplantation of the DBS-hardware is a treatment option of the DBS-WDS when the life-threatening urgency overrides surgical standards. Observation of the syndrome indicates pharmacological unresponsiveness of the dopaminergic system in advanced PD and long-term DBS.

Scientific publications of European neurologists: a survey commissioned by the European Academy of Neurology

BACKGROUND AND PURPOSE

Bibliometric searches may provide an indirect assessment of research in a field or country. The European Academy of Neurology decided to investigate how article production was developing in European countries, as an indicator of neurological vitality.

METHODS

We searched two databases, Scopus and PubMed, for articles published by authors belonging to neurological institutions in all European countries, the USA, Brazil, China and Japan. The search assessed production in the period between 2000 and 2015. We calculated four indicators, i.e. gross neurological product (GNP) (which includes all articles published in any indexed journal), production in top neurological journals, GNP per inhabitant and GNP per gross domestic product.

RESULTS

All indicators greatly increased over time. The European GNP paralleled that of the USA and was higher than those of the other countries. Restricting the search to top neurological journals showed that, since 2012, European production grew faster than that of the USA. Germany had the highest production within Europe, Switzerland had the best ratio between GNP and inhabitants, and The Netherlands had the best ratio between GNP and gross domestic product.

CONCLUSIONS

Although this search had several limitations, the results were so straightforward that we can conclude that European neurology is highly active in the world. Future analyses should compare neurology with other main medical disciplines.

Comparison of EEG and MEG in source localization of induced human gamma-band oscillations during visual stimulus

High frequency gamma oscillations are indications of information processing in cortical neuronal networks. Recently, non-invasive detection of these oscillations have become one of the main research areas in magnetoencephalography (MEG) and electroencephalography (EEG) studies. The aim of this study, which is a continuation of our previous MEG study, is to compare the capability of the two modalities (EEG and MEG) in localizing the source of the induced gamma activity due to a visual stimulus, using a spatial filtering technique known as dynamic imaging of coherent sources (DICS). To do this, the brain activity was recorded using simultaneous MEG and EEG measurement and the data were analyzed with respect to time, frequency, and location of the strongest response. The spherical head modeling technique, such as, the three-shell concentric spheres and an overlapping sphere (local sphere) have been used as a forward model to calculate the external electromagnetic potentials and fields recorded by the EEG and MEG, respectively. Our results from the time-frequency analysis, at the sensor level, revealed that the parieto-occipital electrodes and sensors from both modalities showed a clear and sustained gamma-band activity throughout the post-stimulus duration and that both modalities showed similar strongest gamma-band peaks. It was difficult to interpret the spatial pattern of the gamma-band oscillatory response on the scalp, at the sensor level, for both modalities. However, the source analysis result revealed that MEG3 sensor type, which measure the derivative along the longitude, showed the source more focally and close to the visual cortex (cuneus) as compared to that of the EEG.

Consensus Statement on the classification of tremors. from the task force on tremor of the International Parkinson and Movement Disorder Society

BACKGROUND

Consensus criteria for classifying tremor disorders were published by the International Parkinson and Movement Disorder Society in 1998. Subsequent advances with regard to essential tremor, tremor associated with dystonia, and other monosymptomatic and indeterminate tremors make a significant revision necessary.

OBJECTIVES

Convene an international panel of experienced investigators to review the definition and classification of tremor.

METHODS

Computerized MEDLINE searches in January 2013 and 2015 were conducted using a combination of text words and MeSH terms: "tremor", "tremor disorders", "essential tremor", "dystonic tremor", and "classification" limited to human studies. Agreement was obtained using consensus development methodology during four in-person meetings, two teleconferences, and numerous manuscript reviews.

RESULTS

Tremor is defined as an involuntary, rhythmic, oscillatory movement of a body part and is classified along two axes: Axis 1-clinical characteristics, including historical features (age at onset, family history, and temporal evolution), tremor characteristics (body distribution, activation condition), associated signs (systemic, neurological), and laboratory tests (electrophysiology, imaging); and Axis 2-etiology (acquired, genetic, or idiopathic). Tremor syndromes, consisting of either isolated tremor or tremor combined with other clinical features, are defined within Axis 1. This classification scheme retains the currently accepted tremor syndromes, including essential tremor, and provides a framework for defining new syndromes.

CONCLUSIONS

This approach should be particularly useful in elucidating isolated tremor syndromes and syndromes consisting of tremor and other signs of uncertain significance. Consistently defined Axis 1 syndromes are needed to facilitate the elucidation of specific etiologies in Axis 2. © 2017 International Parkinson and Movement Disorder Society.

Past, present, and future of Parkinson's disease: A special essay on the 200th Anniversary of the Shaking Palsy

This article reviews and summarizes 200 years of Parkinson's disease. It comprises a relevant history of Dr. James Parkinson's himself and what he described accurately and what he missed from today's perspective. Parkinson's disease today is understood as a multietiological condition with uncertain etiopathogenesis. Many advances have occurred regarding pathophysiology and symptomatic treatments, but critically important issues are still pending resolution. Among the latter, the need to modify disease progression is undoubtedly a priority. In sum, this multiple-author article, prepared to commemorate the bicentenary of the shaking palsy, provides a historical state-of-the-art account of what has been achieved, the current situation, and how to progress toward resolving Parkinson's disease. © 2017 International Parkinson and Movement Disorder Society.

Network effects and pathways in Deep brain stimulation in Parkinson's disease

Deep brain stimulation of subthalamic nucleus (STN-DBS) became a standard therapeutic option in Parkinson's disease (PD), even though the underlying modulated network of STN-DBS is still poorly described. Probabilistic tractography and connectivity analysis as derived from diffusion tensor imaging (DTI) were performed together with modelling of implanted electrode positions and linked postoperative clinical outcome. Fifteen patients with idiopathic PD without dementia were selected for DBS treatment. After pre-processing, probabilistic tractography was run from cortical and subcortical seeds of the hypothesized network to targets represented by the positions of the active DBS contacts. The performed analysis showed that the projections of the stimulation site to supplementary motor area (SMA) and primary motor cortex (M1) are mainly involved in the network effects of STN-DBS. An involvement of the "hyperdirected pathway" and a clear delimitation of the cortico-spinal tract were demonstrated. This study shows the effects of STN-DBS in PD distinctly rely on the network connections of the stimulated region to M1 and SMA, motor and premotor regions.

Functional tremor

Functional tremor is the commonest reported functional movement disorder. A confident clinical diagnosis of functional tremor is often possible based on the following "positive" criteria: a sudden tremor onset, unusual disease course, often with fluctuations or remissions, distractibility of the tremor if attention is removed from the affected body part, tremor entrainment, tremor variability, and a coactivation sign. Many patients show excessive exhaustion during examination. Other somatizations may be revealed in the medical history and patients may show additional functional neurologic symptoms and signs. In cases where the clinical diagnosis remains challenging, providing a "laboratory-supported" level of certainty aids an early positive diagnosis. In rare cases, in which the distinction from Parkinson's disease is difficult, dopamine transporter single-photon emission computed tomography (DAT-SPECT) can be indicated.

Comparison of imaging modalities and source-localization algorithms in locating the induced activity during deep brain stimulation of the STN

One of the most commonly used therapy to treat patients with Parkinson's disease (PD) is deep brain stimulation (DBS) of the subthalamic nucleus (STN). Identifying the most optimal target area for the placement of the DBS electrodes have become one of the intensive research area. In this study, the first aim is to investigate the capabilities of different source-analysis techniques in detecting deep sources located at the sub-cortical level and validating it using the a-priori information about the location of the source, that is, the STN. Secondly, we aim at an investigation of whether EEG or MEG is best suited in mapping the DBS-induced brain activity. To do this, simultaneous EEG and MEG measurement were used to record the DBS-induced electromagnetic potentials and fields. The boundary-element method (BEM) have been used to solve the forward problem. The position of the DBS electrodes was then estimated using the dipole (moving, rotating, and fixed MUSIC), and current-density-reconstruction (CDR) (minimum-norm and sLORETA) approaches. The source-localization results from the dipole approaches demonstrated that the fixed MUSIC algorithm best localizes deep focal sources, whereas the moving dipole detects not only the region of interest but also neighboring regions that are affected by stimulating the STN. The results from the CDR approaches validated the capability of sLORETA in detecting the STN compared to minimum-norm. Moreover, the source-localization results using the EEG modality outperformed that of the MEG by locating the DBS-induced activity in the STN.

Detection of steering direction using EEG recordings based on sample entropy and time-frequency analysis

Monitoring driver's intentions beforehand is an ambitious aim, which will bring a huge impact on the society by preventing traffic accidents. Hence, in this preliminary study we recorded high resolution electroencephalography (EEG) from 5 subjects while driving a car under real conditions along with an accelerometer which detects the onset of steering. Two sensor-level analyses, sample entropy and time-frequency analysis, have been implemented to observe the dynamics before the onset of steering. Thus, in order to classify the steering direction we applied a machine learning algorithm consisting of: dimensionality reduction and classification using principal-component-analysis (PCA) and support-vector-machine (SVM), respectively. The results showed an increase of the sample entropy and the estimated power values in the theta and alpha frequency bands, 100 ms before the onset of steering. The detection of steering direction depicted that sample entropy gives a higher classification accuracy (73.5% ±6.8) as compared to that of using the estimated power for theta and alpha frequency bands (62.6% ±5.6).

German registry of paediatric deep brain stimulation in patients with childhood-onset dystonia (GEPESTIM)

BACKGROUND

Data on paediatric deep brain stimulation (DBS) is limited, especially for long-term outcomes, because of small numbers in single center series and lack of systematic multi-center trials.

OBJECTIVES

We seek to systematically evaluate the clinical outcome of paediatric patients undergoing DBS.

METHODS

A German registry on paediatric DBS (GEPESTIM) was created to collect data of patients with dystonia undergoing DBS up to the age of 18 years. Patients were divided into three groups according to etiology (group 1 inherited, group 2 acquired, and group 3 idiopathic dystonia).

RESULTS

Data of 44 patients with a mean age of 12.8 years at time of operation provided by 6 German centers could be documented in the registry so far (group 1 n = 18, group 2 n = 16, group 3 n = 10). Average absolute improvement after implantation was 15.5 ± 18.0 for 27 patients with pre- and postoperative Burke-Fahn-Marsden Dystonia Rating scale movement scores available (p < 0.001) (group 1: 19.6 ± 19.7, n = 12; group 2: 7.0 ± 8.9, n = 8; group 3: 19.2 ± 20.7, n = 7). Infection was the main reason for hardware removal (n = 6). 20 IPG replacements due to battery expiry were necessary in 15 patients at 3.7 ± 1.8 years after last implantation.

DISCUSSION

Pre- and postoperative data on paediatric DBS are very heterogeneous and incomplete but corroborate the positive effects of DBS on inherited and acquired dystonia. Adverse events including relatively frequent IPG replacements due to battery expiry seem to be a prominent feature of children with dystonia undergoing DBS. The registry enables collaborative research on DBS treatment in the paediatric population and to create standardized management algorithms in the future.

Rating Scales for Pain in Parkinson's Disease: Critique and Recommendations

BACKGROUND

We aimed at critically appraising the clinimetric properties of existing pain scales or questionnaires and to give recommendations for their use in Parkinson's disease (PD).

METHODS

Clinimetric properties of pain scales used in PD were systematically evaluated. A scale was classified as 'recommended' if was used in PD, showed adequate clinimetric properties, and had been used by investigators other than the original developers; as 'suggested' if it was used in PD and fulfilled only one other criterion; and as 'listed' if it was used in PD but did not meet the other criteria. Only scales rating pain intensity or for syndromic classification were assessed.

RESULTS

Eleven of the 34 scales initially considered fulfilled inclusion criteria. Among the scales rating pain intensity, the "Brief Pain Inventory short form," "McGill Pain Questionnaire short and long forms," "Neuropathic Pain Symptoms Inventory," "11-point Numeric Rating Scale," "10-cm Visual Analog Scale," and "Pain-O-Meter" were "recommended with caution" because of lack of clinimetric data in PD, whereas the "King's PD Pain Scale" was "recommended." Among scales for pain syndromic classification, the "DN4" was "recommended with caution" because of lack of clinimetric data in PD; the "Leeds Assessment of Neuropathic Symptoms and Signs," "Pain-DETECT," and the "King's PD Pain Scale" were "suggested."

CONCLUSIONS

King's PD pain scale can be recommended for the assessment of pain intensity in PD. Syndromic classification of pain in PD may be achieved by the DN4, but clinimetric data in PD are needed for this scale.

Effect of high-frequency subthalamic neurostimulation on gait and freezing of gait in Parkinson's disease: a systematic review and meta-analysis

The aim of this meta-analysis was to summarize the short- and long-term effects of bilateral deep brain stimulation of the subthalamic nucleus (STN-DBS) on gait and freezing of gait (FOG) in Parkinson's disease and to detect predictors of post-stimulation outcome. A comprehensive review of the literature was conducted up to October 2015 using Medline Ovid databases for studies analyzing the effect of bilateral STN-DBS on FOG and/or gait. Sixteen studies with available data for the gait item (no. 29) of the Unified Parkinson's Disease Rating Scale (UPDRS) and six studies with the FOG item (no. 14) were included. Data were summarized for the following follow-up periods: 6-15, 24-48 and >48 months. For the medication (Med)-Off/stimulation(Stim)-On condition compared with baseline Med-Off, STN-DBS significantly improved gait on average from 2.43 to 0.96, 2.53 to 1.31 and 2.56 to 1.40 points at 6-15, 24-48 and >48 months, respectively (P < 0.05). Pre-operative levodopa responsiveness of UPDRS-III and Med-Off severity of gait were the predictors of this beneficial effect. STN-DBS significantly improved FOG for the Med-Off/Stim-On condition compared with baseline on average from 2.26 to 0.82, 2.43 to 1.13 and 2.48 to 1.38 points at 6-15, 24-48 and >48 months, respectively (P < 0.05). There was no significant effect in the Med-On/Stim-On condition. This meta-analysis showed a robust improvement of gait and FOG by STN-DBS for more than 4 years in the Med-Off/Stim-On condition. No beneficial effect was found for the On state of medication. Pre-operative levodopa responsiveness of global motor performance (UPDRS-III) is the strongest predictor of the effect of deep brain stimulation on gait.

Current concepts of essential tremor

Essential tremor is clinically defined but there is increasing evidence that it is not a unique entity. Its pathophysiology has been studied with many methods but may also vary between subtypes. Neurophysiologically, there is strong evidence that a specific cerebello-thalamo-cortical loop is abnormally oscillating. The cause of its uncontrolled oscillation is not yet understood. The clear proof of a degenerative cause is still lacking and abnormal receptors or other causes of altered non-progressive functional disturbance cannot be excluded. Strong evidence supports the major involvement of the cerebellum and there is ample evidence that GABA is the main neurotransmitter involved in the pathophysiology in ET. Genetics have provided so far only a few rare subtypes which are due to specific mutations but there is no doubt that it is mostly a hereditary condition. There is evidence that the large subgroup of late onset tremor is a separate condition and this tremor is an independent risk factor for earlier mortality and comes with signs of premature aging (aging-related tremor). It will be important to improve phenotyping of patients in more detail possibly to include not only features of the tremor itself but also other clinical assessments like force measurements or cognitive testing. Based on these variables, we may be able to better understand the presumably different mechanisms underlying different variants of the disease.

Platelet Activation and Platelet-Leucocyte Interaction in Patients with Migraine. Subtype Differences and Influence of Triptans

As migraine is the result of an inflammatory mechanism with serotonergic signalling, leucocyte function, platelet function and intercellular communication between those cells is likely to be connected to the final pathway of the disease. We examined P-selectin expression on platelets (platelet activation) and leucocyte-platelet aggregate formation in 72 migraine patients during their attack-free interval and controls using a flow cytometric assay. Patients suffering from migraine without aura had a significantly increased platelet activation and leucocyte-platelet aggregation compared with the control group, unlike the migraine patients with aura. Patients who had taken a triptan within 3 days prior to the investigation showed platelet activation values similar to the control group. The variations in platelet activation patterns of migraine subgroups could indicate different pathomechanisms. Even outside an attack, migraine patients, particularly those without aura, show an increased level of platelet activation which seems to be down-regulated by triptans. This mechanism may account for the triptan-induced increases in headache frequency. The involvement of proinflammatory platelet-leucocyte cross-talk suggests a possible therapeutic strategy using anti-inflammatory drugs.

Pathophysiological Concepts and Treatment of Camptocormia

Camptocormia is a disabling pathological, non-fixed, forward bending of the trunk. The clinical definition using only the bending angle is insufficient; it should include the subjectively perceived inability to stand upright, occurrence of back pain, typical individual complaints, and need for walking aids and compensatory signs (e.g. back-swept wing sign). Due to the heterogeneous etiologies of camptocormia a broad diagnostic approach is necessary. Camptocormia is most frequently encountered in movement disorders (PD and dystonia) and muscles diseases (myositis and myopathy, mainly facio-scapulo-humeral muscular dystrophy (FSHD)). The main diagnostic aim is to discover the etiology by looking for signs of the underlying disease in the neurological examination, EMG, muscle MRI and possibly biopsy. PD and probably myositic camptocormia can be divided into an acute and a chronic stage according to the duration of camptocormia and the findings in the short time inversion recovery (STIR) and T1 sequences of paravertebral muscle MRI. There is no established treatment of camptocormia resulting from any etiology. Case series suggest that deep brain stimulation (DBS) of the subthalamic nucleus (STN-DBS) is effective in the acute but not the chronic stage of PD camptocormia. In chronic stages with degenerated muscles, treatment options are limited to orthoses, walking aids, physiotherapy and pain therapy. In acute myositic camptocormia an escalation strategy with different immunosuppressive drugs is recommended. In dystonic camptocormia, as in dystonia in general, case reports have shown botulinum toxin and DBS of the globus pallidus internus (GPi-DBS) to be effective. Camptocormia in connection with primary myopathies should be treated according to the underlying illness.

Testing the effects of pre-processing on voxel based morphometry analysis

Voxel based morphometry (VBM) is an automated analysis technique which allows voxel-wise comparison of mainly grey-matter volumes between two magnetic resonance images (MRI). Two main analysis processes in VBM are possible. One is cross-sectional data analysis, where one group is compared with another to depict see the regions in the brain, which show changes in their grey-matter volume. Second is longitudinal data analysis, where MRIs, taken at different time points, are compared to see the regions in the brain that show changes in their grey matter volume for one time point with respect to another time point. Both types of analyses require pre-processing steps before performing the statistical analysis. In this study, we examined grey matter differences for patients with blepharospasmus (BFS) before and after treatment, at two different time points. The main evidence base therapy for this condition is the "botulinum toxin" injection in the respective muscles. The main aim of this study was to look at the effects of different pre-processing steps, namely, normalization and smoothing on the results of the longitudinal data analysis. A second aim was to analyze structural grey-matter differences before and after the treatment. Our results showed that the DARTEL normalization and the lower width for smoothing as preprocessing steps delivered pathophysiological plausible results. The longitudinal analysis revealed significant temporal differences after the injection of the botulinum toxin injection mainly in patients with BFS.

Differentiating tremor patients using spiral analyses

Essential tremor follows an autosomal dominant type of inheritance in the majority of patients, yet its genetic basis has not been identified. The age of onset in this tremor is bimodal, one in young age and another when they are old. The old onset is referred to as senile tremor in this study. The precise pathology is still not completely understood for both these tremors. We wanted to develop an easy diagnostic tool to differentiate these two tremors clinically. In this study, the spirals were asked to be drawn by 30 patients, 15 from each group. The spirals were recorded digitally from each hand, with and without the spiral template, using a Wacom intuos version 4 tablets. The aim of the study was to look at the easy diagnostic measures from these spirals to distinguish the two cohorts of patients. The first measure was to use the well-known clinical scores like the number of complete circles without the template, width, height, axis, and degree of severity. The second measure was to estimate the peak frequency and the peak amplitude for the position, velocity, and acceleration data, in the frequency domain. The well-known clinical scores, most of them, did not show any significant difference between the two patient cohorts except the degree of severity which showed significant difference. The peak frequency and the peak amplitude in most of the data were not significantly different between the two cohorts of patients, only the peak amplitude from the acceleration data showed significant difference. Thus, we could use these two parameters to differentiate between the two tremors patient groups, which would be an easy clinical diagnostic tool without the need for any complicated analyses.

Voxel seed coherent source analysis on transient global amnesia patients

Transient global amnesia (TGA) is a rare neurological disorder with a sudden, temporary episode of memory loss which usually occurs in old age. The episodic loss of memory becomes normal after a stipulated time of approximately 24 hours. The precise pathology is not yet completely understood. Moreover, there is no proper neuroimaging method to assess this condition. In this study, the EEG was measured at two time points one with the occurrence of the episode (acute) and the second time point after the patient returns to the normal memory condition (follow-up). The aim of the study was to look at the pathological network involved during the acute phase and the follow up phase in these patients for the five frequency bands, namely, delta, theta, alpha, beta, and gamma. The method used for the source analyses was a beamforming approach called dynamic imaging of coherent sources in the frequency domain. The seed voxel was the lesion area taken from the anatomical MRI of each patient. The cortical and subcortical network comprised of the caudate and cerebellum in case of the delta band frequency. Two temporal sources in case of the theta band. Temporal, medial frontal, parietal, putamen, and thalamus sources were found in case of the alpha band. Prefrontal, parietal, and thalamus sources were found in case of the beta band. Temporal and thalamus in case of the gamma band frequency. All these sources were involved in the acute phase. Moreover, in the follow-up phase the motor area, in all frequency bands except gamma band, was additionally active followed by parietal and occipital regions in alpha and gamma frequencies. The differences involved in the network of sources between the two phases gives us better understanding of this neurological disorder.

Protocol of a randomised delayed-start double-blind placebo-controlled multi-centre trial for Levodopa in EArly Parkinson's disease: the LEAP-study

Background

The aim of this study is to investigate if early treatment with levodopa has a beneficial disease modifying effect on Parkinson’s disease (PD) symptoms and functional health, improves the ability to (maintain) work, and reduces the use of (informal) care, caregiver burden, and costs. Additionally, cost-effectiveness and cost-utility of early levodopa treatment will be assessed.

Methods

To differentiate between the direct symptomatic effects and possible disease modifying effects of levodopa, we use a randomised delayed-start double-blind placebo-controlled multi-centre trial design. Patients with early stage PD whose functional health does not yet necessitate initiation of PD-medication will be randomised to either 40 weeks of treatment with levodopa/carbidopa 100/25 mg TID including 2 weeks of dose escalation or to 40 weeks placebo TID. Subsequently, all patients receive levodopa/carbidopa 100/25 mg TID for 40 weeks. There are 8 assessments: at baseline and at 4, 22, 40, 44, 56, 68, and 80 weeks. The primary outcome measure is the difference in the mean total Unified Parkinson’s Disease Rating Scale scores between the early- and delayed-start groups at 80 weeks. Secondary outcome measures are rate of progression, the AMC Linear Disability Score, side effects, perceived quality of life with the Parkinson’s Disease Questionnaire-39, the European Quality of Life-5 Dimensions (EQ-5D), ability to (maintain) work, the use of (informal) care, caregiver burden, and costs. 446 newly diagnosed PD patients without impaired functional health need to be recruited in order to detect a minimal clinical relevant difference of 4 points on the total UPDRS at 80 weeks.

Discussion

The LEAP-study will provide insights into the possible disease modifying effects of early levodopa.

Trial registration

ISRCTN30518857, EudraCT number 2011-000678-72

Impact of head modeling and sensor types in localizing human gamma-band oscillations

An effective mechanism in neuronal communication is oscillatory neuronal synchronization. The neuronal gamma-band (30-100 Hz) synchronization is associated with attention which is induced by a certain visual stimuli. Numerous studies have shown that the gamma-band activity is observed in the visual cortex. However, impact of different head modeling techniques and sensor types to localize gamma-band activity have not yet been reported. To do this, the brain activity was recorded using 306 magnetoencephalography (MEG) sensors, consisting of 102 magnetometers and 102 pairs of planar gradiometers (one measuring the derivative of the magnetic field along the latitude and the other along the longitude), and the data were analyzed with respect to time, frequency, and location of the strongest response. The spherical head models with a single-shell and overlapping spheres (local sphere) have been used as a forward model for calculating the external magnetic fields generated from the gamma-band activity. For each sensor type, the subject-specific frequency range of the gamma-band activity was obtained from the spectral analysis. The identified frequency range of interest with the highest gamma-band activity is then localized using a spatial-filtering technique known as dynamic imaging of coherent sources (DICS). The source analysis for all the subjects revealed that the gradiometer sensors which measure the derivative along the longitude, showed sources close to the visual cortex (cuneus) as compared to the other gradiometer sensors which measure the derivative along the latitude. However, using the magnetometer sensors, it was not possible to localize the sources in the region of interest. When comparing the two head models, the local-sphere model helps in localizing the source more focally as compared to the single-shell head model.

Comparison of causality analysis on simultaneously measured fMRI and NIRS signals during motor tasks

Brain activity can be measured using different modalities. Since most of the modalities tend to complement each other, it seems promising to measure them simultaneously. In to be presented research, the data recorded from Functional Magnetic Resonance Imaging (fMRI) and Near Infrared Spectroscopy (NIRS), simultaneously, are subjected to causality analysis using time-resolved partial directed coherence (tPDC). Time-resolved partial directed coherence uses the principle of state space modelling to estimate Multivariate Autoregressive (MVAR) coefficients. This method is useful to visualize both frequency and time dynamics of causality between the time series. Afterwards, causality results from different modalities are compared by estimating the Spearman correlation. In to be presented study, we used directionality vectors to analyze correlation, rather than actual signal vectors. Results show that causality analysis of the fMRI correlates more closely to causality results of oxy-NIRS as compared to deoxy-NIRS in case of a finger sequencing task. However, in case of simple finger tapping, no clear difference between oxy-fMRI and deoxy-fMRI correlation is identified.